Shortly before landing, Bob Hayden and a flight attendant had agreed on a signal: When she waved the plastic handcuffs, he would discreetly leave his seat and restrain an unruly passenger who had frightened some of the 150 people on board a Minneapolis-to-Boston flight Saturday night with erratic behavior.

Hayden, a 65-year-old former police commander, had enlisted a gray-haired gentleman sitting next to him to assist. The man turned out to be a former US Marine.

"I had looked around the plane for help, and all the younger guys had averted their eyes. When I asked the guy next to me if he was up to it, all he said was, 'Retired captain. USMC.' I said, 'You'll do,'

" Hayden recalled. "So, basically, a couple of grandfathers took care of the situation."

The incident on Northwest Airlines Flight 720 ended peacefully, but not before Hayden, a former Boston police deputy superintendent and former Lawrence police chief, and the retired Marine had handcuffed one man and stood guard over another until the plane touched down safely at Logan International Airport around 7:50 p.m.

State Police troopers escorted two men off the flight. Trooper Thomas Murphy, a State Police spokesman, said one of the men was transported to Massachusetts General Hospital for "an unspecified medical issue, possibly mental health."

He said State Police detectives will investigate whether the man's behavior should be treated as a medical or criminal matter. A second man escorted off the plane identified himself as the unruly passenger's brother. Murphy said police would not release the names of the men, who Hayden said appeared to be in their 30s or 40s.

Dean Breest, a spokesman for Northwest, confirmed that "there was an incident that required State Police to come on board the aircraft" but declined further comment.

Hayden said the unruly man's behavior upset some passengers. One told Hayden the man had said, "Your lives are going to change today forever," as he shouted and refused to take his seat before takeoff and at various times during the nearly three-hour flight. He said that at one point the man lay on his back and was screaming, moaning, and thrashing on the floor.

"Some people were crying," Hayden said. "I thought it might be a diversion. I kept scanning the back of the plane to see if anyone was going to rush forward. The flight attendants did a great job, literally surrounding the two guys who were making all the noise. I told one of the flight attendants I was a retired police officer and would be willing to assist, so we agreed on a signal."

When the captain announced preparations for landing, the man jumped up shouting, the flight attendant held up the handcuffs, and Hayden and the Marine came bounding down the aisle. Hayden said he and the retired Marine, whose name he never got, received an ovation from fellow passengers, and "some free air miles."

Hayden's wife of 42 years, Katie, who was also on the flight, was less impressed. Even as her husband struggled with the agitated passenger, she barely looked up from "The Richest Man in Babylon," the book she was reading.

"The woman sitting in front of us was very upset and asked me how I could just sit there reading," Katie Hayden said. "Bob's been shot at. He's been stabbed. He's taken knives away. He knows how to handle those situations. I figured he would go up there and step on somebody's neck, and that would be the end of it. I knew how that situation would end. I didn't know how the book would end."